Proprotor flapping control systems for tiltrotor aircraft

Abstract

A flapping control system for a proprotor assembly of a tiltrotor aircraft includes one or more sensors operable to detect one or more flight parameters of the tiltrotor aircraft to form sensor data. The sensors include a proprotor flapping sensor to detect a proprotor flapping measurement. The flapping control system includes a flapping control module in data communication with the sensors. The flapping control module includes a maneuver detection module to detect whether the tiltrotor aircraft is in a maneuver mode using the sensor data. The flapping control module identifies a maneuver flapping threshold associated with the maneuver mode. The flapping control module generates a swashplate command using the proprotor flapping measurement and the maneuver flapping threshold, and sends the swashplate command to the proprotor assembly to reduce flapping of the proprotor assembly.

What is claimed is: 
     
       1. A flapping control system for a proprotor assembly of a tiltrotor aircraft comprising:
 one or more sensors operable to detect one or more flight parameters of the tiltrotor aircraft to form sensor data, the one or more sensors including a proprotor flapping sensor operable to detect a proprotor flapping measurement; and 
 a flapping control module in data communication with the one or more sensors, the flapping control module including a maneuver detection module operable to detect whether the tiltrotor aircraft is in a maneuver mode using the sensor data, the flapping control module operable to identify a maneuver flapping threshold associated with the maneuver mode; 
 wherein the flapping control module is further operable to generate a swashplate command using the proprotor flapping measurement and the maneuver flapping threshold and send the swashplate command to the proprotor assembly to reduce flapping of the proprotor assembly. 
 
     
     
       2. The flapping control system as recited in  claim 1  wherein the one or more sensors further comprise at least one sensor selected from the group consisting of a roll rate sensor, a pitch rate sensor, a yaw rate sensor, a normal acceleration sensor, a blowback flapping sensor and an airspeed sensor. 
     
     
       3. The flapping control system as recited in  claim 1  wherein the maneuver detection module is further operable to detect that the tiltrotor aircraft is in the maneuver mode in response to anticipating performance of a maneuver by the tiltrotor aircraft using the sensor data. 
     
     
       4. The flapping control system as recited in  claim 1  wherein the maneuver detection module is further operable to identify a proportional relationship between one or more flight parameters of the sensor data and flapping of the proprotor assembly; and
 wherein the flapping control module is further operable to generate the swashplate command using the proportional relationship. 
 
     
     
       5. The flapping control system as recited in  claim 1  wherein the maneuver flapping threshold further comprises a longitudinal component and a lateral component, the longitudinal maneuver flapping threshold differing from the lateral maneuver flapping threshold. 
     
     
       6. The flapping control system as recited in  claim 5  wherein the lateral maneuver flapping threshold is less than the longitudinal maneuver flapping threshold. 
     
     
       7. The flapping control system as recited in  claim 5  wherein the lateral maneuver flapping threshold further comprises inboard and outboard components and wherein the inboard lateral maneuver flapping threshold is less than the outboard lateral maneuver flapping threshold. 
     
     
       8. The flapping control system as recited in  claim 1  wherein the flapping control module is further operable to determine a flapping error using the proprotor flapping measurement and the maneuver flapping threshold and wherein the flapping control module is further operable to generate the swashplate command using the flapping error. 
     
     
       9. The flapping control system as recited in  claim 1  wherein the flapping control module is further operable to identify at least one of a proportional control gain used in generating the swashplate command or an integral control gain used in generating the swashplate command. 
     
     
       10. The flapping control system as recited in  claim 1  wherein the swashplate command reduces the flapping of the proprotor assembly to equal or less than the maneuver flapping threshold. 
     
     
       11. A tiltrotor aircraft comprising:
 a fuselage; 
 a wing coupled to the fuselage; 
 at least one propulsion assembly coupled to the wing, the at least one propulsion assembly each including a proprotor assembly; 
 one or more sensors operable to detect one or more flight parameters of the tiltrotor aircraft to form sensor data, the one or more sensors including a proprotor flapping sensor operable to detect a proprotor flapping measurement; and 
 a flight control computer including a flapping control module in data communication with the one or more sensors, the flapping control module including a maneuver detection module operable to detect whether the tiltrotor aircraft is in a maneuver mode using the sensor data, the flapping control module operable to identify a maneuver flapping threshold associated with the maneuver mode; 
 wherein the flapping control module is further operable to generate a swashplate command using the proprotor flapping measurement and the maneuver flapping threshold and send the swashplate command to the proprotor assembly to reduce flapping of the proprotor assembly. 
 
     
     
       12. The tiltrotor aircraft as recited in  claim 11  wherein the proprotor assembly further comprises a plurality of proprotor blade assemblies; and
 wherein the proprotor flapping sensor is further operable to measure a flapping angle of the proprotor blade assemblies to form the proprotor flapping measurement. 
 
     
     
       13. The tiltrotor aircraft as recited in  claim 11  wherein the at least one propulsion assembly includes a pylon assembly movable between a generally vertical orientation in helicopter flight mode and a generally horizontal orientation in airplane flight mode, the pylon assembly including the proprotor assembly, the proprotor assembly including a plurality of proprotor blade assemblies; and
 wherein the flapping control module is further operable to reduce flapping of the proprotor blade assemblies while the tiltrotor aircraft is in the airplane mode to prevent contact between the proprotor blade assemblies and the wing. 
 
     
     
       14. The tiltrotor aircraft as recited in  claim 11  wherein the maneuver detection module is further operable to detect whether the tiltrotor aircraft is in one of a steady state mode or the maneuver mode. 
     
     
       15. The tiltrotor aircraft as recited in  claim 11  wherein the wing further comprises first and second outboard ends respectively having first and second propulsion assemblies coupled thereto and wherein the flapping control module is operable to reduce flapping of the proprotor assemblies for the first and second propulsion assemblies. 
     
     
       16. A method for controlling flapping of a proprotor assembly of a tiltrotor aircraft comprising:
 receiving a proprotor flapping measurement from a proprotor flapping sensor; 
 identifying a maneuver flapping threshold in response to detecting that the tiltrotor aircraft is in a maneuver mode; 
 determining a flapping error using the proprotor flapping measurement and the maneuver flapping threshold; 
 determining a swashplate command using the flapping error; and 
 sending the swashplate command to the proprotor assembly to reduce flapping of the proprotor assembly. 
 
     
     
       17. The method as recited in  claim 16  wherein identifying the maneuver flapping threshold further comprises identifying at least one of a longitudinal maneuver flapping threshold or a lateral maneuver flapping threshold. 
     
     
       18. The method as recited in  claim 16  wherein detecting that the tiltrotor aircraft is in the maneuver mode further comprises at least one of detecting that the tiltrotor aircraft is in the maneuver mode using sensor data from one or more sensors or anticipating the maneuver mode using sensor data from one or more sensors. 
     
     
       19. The method as recited in  claim 16  wherein determining the swashplate command further comprises at least one of determining the swashplate command using sensor data from one or more sensors, determining the swashplate command using a proportional control gain or determining the swashplate command using an integral control gain. 
     
     
       20. The method as recited in  claim 16  further comprising identifying a proportional relationship between flapping of the proprotor assembly and one or more parameters of sensor data from one or more sensors and determining the swashplate command based on the proportional relationship. 
     
     
       21. The method as recited in  claim 16  wherein sending the swashplate command to the proprotor assembly to reduce flapping of the proprotor assembly further comprises sending the swashplate command to the proprotor assembly to reduce the flapping error to substantially zero.